One child has tested positive for enterovirus D68 at Toronto's Hospital for Sick Children, doctors confirmed Wednesday, as they also revealed that the hospital has had seven cases of EV-D68 since late August.

Last week, SickKids said it was testing a total of three children, all under the age of ten, for the virus. In addition to the positive result, another patient tested negative while physicians are still awaiting results for the third child.

The virus commonly causes a variety of mild cold-like symptoms, such as coughing, running nose or trouble breathing. But Enterovirus D68 is a part of a larger group of viruses that cause similar symptoms, some of which are associated with neurological problems, including muscle weakness and meningitis.

Enterovirus D68 has recently been connected to clusters of confirmed outbreaks of respiratory illness and muscle weakness among children in California, Colorado, B.C., Alberta, Saskatchewan and Manitoba.

Last week, McMaster Children’s Hospital in Hamilton, Ont., confirmed they are testing four patients suspected of contracting the virus after they exhibited muscle weakness. Since Aug. 28, there have been 139 confirmed cases in the Hamilton area.

In a statement that accompanied a press conference Wednesday, associate pediatrician-in-chief at SickKids Dr. Jeremy Friedman said that "it is still early on in the treatment" of the patients with muscle weakness, "but we are seeing some improvement in some patients." He declined to comment on specific cases.

“Certainly we know that enterovirus D68 in the vast majority of children is a very mild illness and most patients will just have some cough and cold symptoms,” Friedman said to reporters.

What continues to puzzle doctors, Friedman admits, is the polio-like systems of extreme muscle weakness that some of the young patients are experiencing.

“We know that muscle weakness itself is not an uncommon problem in children, and there certainly are lots of different potential causes. I think to be honest at the moment its pretty early in the grand scheme of things to really have a full understanding.”

Friedman also said that the hospital has had seven confirmed cases of EV-D68 since late August.

Last week, SickKids provided some advice to parents who may be concerned about enteroviruses.

“If your child is recovering from a respiratory illness but then suddenly develops a new fever, or difficulty breathing you should seek medical attention,” a statement released by the hospital read.

“The best way to protect yourself and your children against enteroviruses is to wash your hands regularly with soap and water. If soap and water are not available, use a hand sanitizer.”